Envelop for storage batteries.



NITED STATES Fries.

PATENT ENVELOP FOR STORAGE BATTERIES.

SPECIFICATION forming part of Letters Patent N 0. 649,003, dated 8,1906.

Application filed October '7, 1899. Serial No. 732,860. (No specimens.)

To all "whom it may concern:

Be it known that I, ELMER A. SPERRY, acitizen of the United States,residing at Cleveland, in the county of Ouyahoga and State of Ohio, haveinvented certain new and useful Improvements in CelluloseNitrate-Cellulose Euvelops for Elements of Storage Batteries, of whichthe following is a specification.

My invention relates to separators or envelops for elements ofbatteries; and it consists in an improved material of which suchseparators or envelops may be constructed, the characteristics of whichare fully described in the following specification,the novelty beingpointed out in the claims hereto annexed. It has been found that inbattery elements,especially storage-battery elements, the activematerial more or less readily disintegrates and tends to fall from theplate, accumulating in the bottom of the cell. It has furthermore beenfound that with an envelop, if properly constructed from substancepermeable to the electrolyte and such as not to interfere with thetraverse of the ions, this material or substance may be retainedmechanically in position, and while on the one hand the action isentirely unimpeded on the other the active material is retained andthecapacity of the battery does not deteriorate, as in the case wherethe active material is allowed to fall away from the plate or electrode.For this purpose I have used cellulose of special form and of such amaterial and structure as will retain its rigidity and inflexibility toa considerable degree. This I have found is best attained by using purecellulose and in treating fiber in which the noncellulosic constituentsbelong to the class of aldehydes and which I remove by the action ofsulfurous acid, yielding thereby a fiber in which the ordinary strengthis entirely preserved and one that can be used for the purpose and inthe manner described. I have found that fibers treated with alkalineprocesses are short, brittle, and not suitable for battery purposes,especially when used in connection with a sulfuric-acid electrolyte. Ithas also been found that the individual fibers are rendered to aconsiderable extent more inert by being subjected to the action ofsulfurous acid a second time with an intervening washing. To distinguishthis product from the ordinary and less inert forms of sulfite fiber, Icall it double sulfite fiber. In this way the aldehydes are morethoroughly eliminated and the fiber is found to be almost perfectly inert in the liquid electrolyte described and un-' affected by the nascentoxygen and hydrogen developed at the poles,while thisfiber is found toyield excellent results, especially when cor rugate'd or ribbed andtreated and utilized as described in my application for United Statespatent,- Serial No. 689,057, filed August 19, 1898. I have found,however, that the stiifness and general durability of the envelop may bestill further improved by the addition of pyroxylin. This I prefer tomake of the longer and smaller fibered grade of cotton -as, forinstance, sea=island cotton which is prepared in a peculiar manner inregard to three features.

First. The nitrogenizing process is carried on to a point where just theright amount of nitrogen is present, giving the fiber a maximumtenacity, as is well known in the art.

Second. The flexibility of the pyroxyliu fiber I find to be somewhatimproved by add ing a trifle of Vaseline; but with some processes ofpulping and mixture with the cellulose this is found to beobjectionable. In some instances, however, the pyroxylin fiber sotreated may be used with success.

Third. During the latter part of the process, or, in fact, in any partof the process of nitrogenizing or in the washing, the fiber is treatedwith just sufficient nitrobenzol or equivalent to render the same notspontaneously explosive; but this is not necessary to the invention, andsome of the special processes and treatment described in connection withthe preparation of pyroxylin fiber may be eliminated and others used,and the invention extends to such use. Pyroxylin in the fiber form isthen mechanically mixed or interspersed throughout the mass 'ofcellulose,distributed as equally as possibly, so that the cellulose whenused in sheet form will be found to have an almost unbroken network,

web, or felting of the pyroxylin fiber. This I find increases therigidity and indestructibility of a sheet to a very marked degree andincreases the life of the envelop in a proportion considerably in excessof the increase in cost. I do not care to limit myself to any exactpercentage or proportion of the mixture of pyroxylin and cellulose, asfor different purposes and different electrolytes and differentconstructions and materials employed in batteries this may be variedthrough wide limits.

It is sometimes found desirable to increase the rigidity orinflexibility of the sheet or envelop in one line more than anotherwithin the sheet. This I have been enabled to accomplish by a unilineardisposition of the fibers within the sheet-accomplished, preferably, bya flowing or so directing the Water upon the pulping or matrix blanketthat the majority of the fibers will take up a single unilineardirection within such matrix and eventually within the sheet. This doesnot mean that all the fibers in the sheet are parallel; but there is adirection easily discernible which indicates the direction of morefibers than any other line within the sheet, andthe sheet is found to bemore rigid to a bending moment applied at right angles to this line.When the matrix so constructed is prepared for use in sheet form, Iprefer to subject it to a considerable pressure, which may be done inany well-known way, either by passingit through rollers or betweenplates at any point in the process of manufacture, andI find that thedensity and stability of the sheet after submersion in the electrolyteare improved if the sheet is subjected to the combined action of heatand pressure. For some special purposes it is found desirable toincrease its rigidity or inflexibility in one line more than another.This I accomplish by (in addition to the above-named processes. touchingthis point) corrugating the sheet in any of the well-known manners. Thismay be done by using a ribbed blanket on the pulping-machine or bycorrugated rollers in the rolling process above referred to. I do notcare to limit myself to any particular process of corrugation or styleor configuration of the irregularity of surface constituting thecorrugation.

I have employed the term pyroxylin as indicatin g the various forms ofcellulose nitrates or nitrogen cellulose. The hexanitrates and others inthe series may be employed. The only point as to the exact constituentsof the compound is that which taken with the particular fiber originallyemployed will give a nitrogen cellulose of the maximum strength,durability, and tenactity. The reason why I prefer to use the Wordpyroxylin in this case as a generic term is that in its preferred form,not being spontaneously explosive and eonsideringits mechanical usesonly, the term guncotton would be misleading, and again using thegeneric term nitrogen cellulose it brings throughout the specificationand claims in juxtaposition two expressions con taining the wordcellulose, which might lead to confusion.

It will be readily understood that while it is designed to use the aboveparts in the relation shown, yet some may be used Without the others,and the invention extends to such use. It will, furthermore, be readilyunderstood that while the detailed construction has been described withmore or less minuteness, yet the invention should be in no wiserestricted to the exact methods and details described, but rather shouldbe limited only in scope, as indicated in the claims.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is.-

1. An envelop or separator for elements of batteries, consisting of anagglomeration of pyroxylin fiber and cellulose fiber in sheet form.

. 2. An envelop or separator for elements of batteries, consisting of adesiccated agglomeration of moistened pyroxylin fiber and cellulosefiber in sheet form.

3. An envelop or separator for elements of batteries, consisting of acompressed agglomeration of pyroxylin fiber and cellulose fiber in sheetform.

4:. An envelop or separator for elements of batteries, consisting of amixture of pyroxyliu fiber and sulfite fiber in sheet form.

5. An envelop or separator for elements of batteries, consisting of amixture ol'pyroxylin fiber and cellulose in sheet form, having one ormore surfaces ribbed or corrugated.

6. An envelop or separator for elements of batteries, consisting of amechanical mixture of pyroxylin fiber and cellulose fiber,tl1e fibers ofthe cellulosic element being parallelly disposed within the mass.

7. An envelop or separator for elements of batteries, consisting of amechanical mixture of pyroxylin fiber and cellulose fiber, both oftheaforesaid fibers being parallelly disposed Within the mass.

8. As an article of man ufactu re, a separator or envelop for elementsof batteries, consistin g of a network or matted mass ofcellulosenitrate fiber impermeable to the electrolyte, interspersed withcellulose fiber, permeable to the electrolyte, substantially asspecified.

ELMIJR A. SPERRY. Witnesses:

W. S. RooERs, H. W. LAMBLEY.

